Messages in this thread Patch in this message | | | Date | Fri, 5 Jul 2013 02:54:29 -0700 | From | tip-bot for Stephane Eranian <> | Subject | [tip:perf/urgent] perf: Fix interrupt handler timing harness |
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Commit-ID: e5302920da9ef23f9d19d4e9ac85704cc25bee7a Gitweb: http://git.kernel.org/tip/e5302920da9ef23f9d19d4e9ac85704cc25bee7a Author: Stephane Eranian <eranian@google.com> AuthorDate: Fri, 5 Jul 2013 00:30:11 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Fri, 5 Jul 2013 08:54:43 +0200
perf: Fix interrupt handler timing harness
This patch fixes a serious bug in:
14c63f17b1fd perf: Drop sample rate when sampling is too slow
There was an misunderstanding on the API of the do_div() macro. It returns the remainder of the division and this was not what the function expected leading to disabling the interrupt latency watchdog.
This patch also remove a duplicate assignment in perf_sample_event_took().
Signed-off-by: Stephane Eranian <eranian@google.com> Cc: peterz@infradead.org Cc: dave.hansen@linux.intel.com Cc: ak@linux.intel.com Cc: jolsa@redhat.com Link: http://lkml.kernel.org/r/20130704223010.GA30625@quad Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 1db3af9..1833bc5 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -182,7 +182,7 @@ void update_perf_cpu_limits(void) u64 tmp = perf_sample_period_ns; tmp *= sysctl_perf_cpu_time_max_percent; - tmp = do_div(tmp, 100); + do_div(tmp, 100); atomic_set(&perf_sample_allowed_ns, tmp); } @@ -232,7 +232,7 @@ DEFINE_PER_CPU(u64, running_sample_length); void perf_sample_event_took(u64 sample_len_ns) { u64 avg_local_sample_len; - u64 local_samples_len = __get_cpu_var(running_sample_length); + u64 local_samples_len; if (atomic_read(&perf_sample_allowed_ns) == 0) return;
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